if you set it to the finest setting, it probably is. i use it to grind coffee for my piston machine, and it should be pretty fine there. the coffee turns out very well with it.
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I almost only drink coffee from the Bialetti, which I use in all sizes.
The fineness of grind can be adjusted finely enough for this, it's no problem. I would specify the finest grind strength with level 1.5-2 for a grinder that is always available at the Coop or Migros.